This invention relates to voltage regulators for AC generators and, more particularly, to a voltage regulator for an AC generator that provides power to at least two different loads at different voltages.
Voltage regulation of the output power of AC generators is usually effected by controlling the magnitude of the field current to the exciter winding of the generator. If the load on the generator increases, causing a drop in a selected voltage, that condition is detected and the field current is increased, causing the output voltage to return to the selected voltage. Similiarly, if the load on the generator is reduced, causing the voltage to increase above the selected voltage, the magnitude of the field current is reduced, thereby decreasing the output voltage.
If a single AC generator is to provide power to at least two loads at different voltage levels, it becomes necessary to decide which voltage should control the field current. If one voltage suddenly decreases significantly and the field current is increased to drive the decreasing voltage back within its selected range, the voltage to the other load(s) may become undesirably excessive.
Many voltage regulators employ a summing-type control system wherein signals representative of the individual voltages or other control variables are summed to provide a field current representing the average of the individual variables. This type of control system makes independent compensation of the individual voltages difficult and provides a mixed error signal, making effective verification testing difficult.